1. Field of the Invention
This invention relates to a bicycle, and more particularly, a bicyle having a double power train which can propel the bicycle forward with one power train, and forward and backward with the other power train for various purposes such as bicycle games and physical exercises, in addition to normal running.
2. Description of the Prior Art
There are hitherto a bicycle of various types, such as a normal type, racing type, off-road type and game type. However, the bicyle of these types is unlikely to be used for an unexpected purpose. That is, when the bicyle is designed for a daily use, it is unlikely to be used for a bicycle game such as a so-called cycle soccer and a cycle-cross, in which a special function is required.
A general structure of a commonly used bicyle will be described hereinafter in conjunction with FIGS. 1 to 3, in which elements of the present invention are also shown.
A sprocket wheel 3 has a larger diameter and is fixed to a driving crank axle (not shown) which is positioned at a lower and center portion of a body 1. A sprocket wheel 4 has a smaller diameter and is fixed to a boss member 13 of a rear tire 2 via a ratchet mechanism (not shown). An endless chain 5 is wound around the sprocket wheel 4 of the rear tire 2 and the sprocket wheel 3 on the driving crank axle. Pedals 9 and 9' mounted to both sides of the driving crank axle are rotated by a rider to transmit propelling force to the rear tire 2 via the driving crank axle and the chain. In this regard, the rachet mechanism transmits the force from the sprocket wheel 3 to the rear tire 2, when the pedals 9, 9' are rotated in such a direction that the bicycle is propelled forward via the rear tire 2. Contrarily, when the pedals 9 and 9' are rotated in the reverse direction, the force is not transmitted to the rear tire 2 with the ratchet mechanism. As a result, the rear tire 2 comes into an idling state.
With the above structure, the bicycle is not propelled backward by rotation of the pedals 9 and 9', since the ratchet mechanism intervenes the transmitting of the propelling force. Therefore, when the bicycle, which can be propelled forward and backward by the force effected by the pedals 9 and 9', is needed in the cycle soccer, cycle-cross, it is necessary to prepare the bicycle of a different type.